No abstract

The magnetic ordering at the surface of epitaxial Cr overlayers on Fed 00) is studied by spinpolarized electron-energy-loss spectroscopy. The exchange asymmetry oscillates with the thickness of the Cr overlayer with a period of about two atomic layers, proving directly that the surface Cr layer has a net ferromagnetic moment and that successive layers order antiferromagnetically. The exchange asymmetry is predominantly due to spin-flip scattering. The spin-flip spectrum broadens toward lower energy with increasing thickness, suggesting that Cr may have a surface-enhanced magnetic moment.